Combustor structure for igniters

ABSTRACT

In a structure of a burning portion of an alcohol-fueled ignitor provided with a wick for drawing up fuel alcohol in a fuel reservoir by capillarity from one end portion thereof to the other end portion and burning the fuel alcohol at the other end portion, the wick is formed of glass fibers and said the other end portion of the wick at which the fuel alcohol is burnt is exposed in a surface area of 30 mm 2  to 170 mm 2 .

FIELD OF THE INVENTION

This invention relates to a structure of a burning portion at the tip ofa wick of an ignitor such as a cigarette lighter in which fuel alcoholcontained in a fuel reservoir is drawn up through the wick bycapillarity and is burnt at the tip of the wick.

More particularly, this invention relates to a form of a burningportion, of an ignitor such as a cigarette lighter using fuel liquidcontaining alcohol as a main component, suitable for obtaining optimalburning.

BACKGROUND OF THE INVENTION

As fuel for an ignitor such as a cigarette lighter, there is generallyused fuel alcohol such as ethyl alcohol, fuel benzine such as petroleumbenzine, or liquefied gas fuel such as butane gas, propane gas or thelike.

Performance, convenience of handling and design properties of ignitorsdiffer depending on the kind of fuel used.

For example, in the case of fuel benzine which is a mixture of petroleumbenzine series hydrocarbons different in boiling point, benzinecomponents lower in boiling point are mainly volatilized at thebeginning of use and the volatile components change to those of higherboiling points. Accordingly, the composition of the fuel remaining inthe ignitor changes with the burning time, which causes change in theflame length. The same is the case with gasoline. Further since benzineand gasoline are high in volatility, a closed structure for suppressingvolatilization of fuel liquid from the fuel storage portion and/or thewick is required in an ignitor where benzine or gasoline is used as thefuel liquid. When closure of the closed structure is insufficient, thefuel liquid is soon lost and the fuel liquid must be frequentlyreplenished. Further some people are not fond of the peculiar odor ofbenzine and gasoline.

In the case of liquefied gas fuel, the pressure of gas is high in theoperating temperature range of the ignitor and accordingly the fuelreservoir must be pressure-resistant. Further, the flame length changeswith change in the gas pressure which logarithmically largely changeswith change in the temperature, and large fluctuation in the flamelength with change in the temperature has been a problem with a gasignitor. In order to overcome this problem, the fuel supply system ofthe ignitor must be provided with a special temperature correctionmeans, which complicates the structure of the ignitor and adds to thecost.

The alcohol fuel mainly comprises monovalent lower alcohol such as ethylalcohol, methyl alcohol, propyl alcohol or the like and is liquid atnormal temperatures and is relatively low in vapor pressure.Accordingly, an alcohol-fueled ignitor need not be pressure-resistant inits fuel reservoir, and the fuel storage portion and/or the wick haveonly to be closed to such an extent that volatilization of the alcoholfuel can be suppressed. Accordingly, the alcohol-fueled ignitor can besimpler in structure and can be manufactured at lower cost.

In the alcohol-fueled ignitor, the alcohol fuel is supplied from thefuel reservoir to the burning portion through a wick which is of an opencell cellular material or of a bundle of thin fibers. The alcohol fuelis drawn up from the lower end portion of the wick and supplied to theupper end portion of the wick through the open cell or the fine spacesbetween the fibers by capillarity.

More specifically, the wick is formed by twisting fibers, by bundlingglass fibers, or by wrapping a bundle of glass fibers by cotton yarnsand fixing the cotton yarns to the glass fiber bundle by winding thinmetal wire around the cotton yarns.

In an ignitor in accordance with a prior art in which fuel liquidcontaining therein alcohol as a main component thereof is used, thestructure of the wick should be as simple as possible so that thequality of the wick is uniform and the wicks can be manufactured at lowcost since the structure of the wick is related to the burningproperties of the ignitor. For this purpose, it is preferred that thewick is formed of glass fibers or ceramic fibers.

In an ignitor using such a wick, an initial flame length just after thefuel is ignited, change of the flame length, the maximum flame lengthand the like vary depending upon the material, dimensions and shape ofthe wick, and accordingly the wick should be arranged to meet desiredproperties of the ignitor.

That is, in the alcohol-fueled ignitor such as a cigarette lighter, fuelon the surface of the wick starts burning with flame upon ignitionthereof. The flame length at this time is taken as an initial flamelength.

Then the wick is heated by the burning and the amount of fuelvolatilizing from the surface of the wick increases, whereby the flamelength increases. However increase in temperature at the surface of thewick gets equilibrated and stops as the burning continues, and increasein the flame length is saturated and the flame length reaches asaturated flame length. As fuel on the surface of the wick burns andconsumes, fuel inside the wick is dispersed toward the surface of thewick and fuel in the fuel reservoir is drawn up through the lower endportion of the wick.

When consumption of fuel at the surface of the wick balances supply offuel from the inside of the wick and supply of fuel from the fuelreservoir, burning continues in the equilibrated state and the flamelength is stabilized. To the contrast, when fuel consumption at thesurface of the wick exceeds fuel supply from the inside of the wick, theflame length becomes shorter than the initial flame length and getsequilibrated at a level according to the fuel supply or the flame isquenched.

In view of the foregoing observations and description, the primaryobject of the present invention is to provide a structure of a burningportion of an alcohol-fueled ignitor which is suitable for obtainingoptimal burning.

In the case of a cigarette lighter, preferably the flame length isinitially at least about 20 mm and increases to about 25 mm in 10seconds or so. Further it is preferred that the saturated flame length,that is, the flame length when the wick is heated to an equilibriumtemperature, be about 60 mm to 70 mm (about 50 mm to 70 mm according tothe purpose of the ignitor) at most. In order to meet theserequirements, the wick should have the capability of drawing up fuelliquid and retaining the same and should be heat-resistant. Further, thewick should be of such a form that the aforesaid burning conditions canbe realized.

SUMMARY OF THE INVENTION

In accordance with one aspect of the present invention, there isprovided a structure of the burning portion of an alcohol-fueled ignitorprovided with a wick for drawing up fuel alcohol in a fuel reservoir bycapillarity from one end portion thereof to the other end portion andburning the fuel alcohol at the other end portion wherein theimprovement comprises that the wick is formed of glass fibers and saidthe other end portion of the wick at which the fuel alcohol is burnt isexposed in a surface area of 30 mm² to 170 mm ².

In the case where the ignitor is a cigarette lighter, it is preferredthat said the other end portion of the wick is exposed in a surface areaof 30 mm² to 100 mm².

In accordance with another aspect of the present invention, there isprovided a structure of the burning portion of an alcohol-fueled ignitorprovided with a wick for drawing up fuel alcohol in a fuel reservoir bycapillarity from one end portion thereof to the other end portion andburning the fuel alcohol at the other end portion, wherein theimprovement comprises that the wick is formed of ceramic fibers and saidthe other end portion of the wick at which the fuel alcohol is burnt isexposed in a surface area of 40 mm² to 170 mm².

In the case where the ignitor is a cigarette lighter, it is preferredthat said the other end portion of the wick is exposed in a surface areaof 40 mm² to 100 mm².

With the structure of the burning portion of the ignitor, the burningproperties can be held in an optimal state where the flame length isinitially about 20 mm, is increased to about 25 mm in about 10 seconds,and is kept about 60 mm in the saturated state, by virtue of the factthat the burning end portion of the wick at which the fuel alcohol isburnt is exposed in a surface area of 30 mm² to 170 mm² (30 mm² to 100mm² in the case of a cigarette lighter) when the wick is of glass fibersor that the burning end portion of the wick at which the fuel alcohol isburnt is exposed in a surface area of 40 mm² to 170 mm² (40 mm² to 100mm² in the case of a cigarette lighter) when the wick is of ceramicfibers.

Especially when the ignitor is a cigarette lighter, it is preferred thatthe overall size of the cigarette lighter be as small as possible, andaccordingly dimensions and the shape of the structure of the burning endportion are limited. Therefore, by defining the circumference, the outerdiameter and/or the amount of projection of the burning end portion ofthe wick so that the surface area of the burning end portion fallswithin the aforesaid range, the cigarette lighter can be miniaturizedand manufactured at low cost while obtaining optimal burning properties.

It is preferred that the circumference of the burning end portion of thewick be in the range of 6 mm to 20 mm, the outer diameter of the burningend portion of the wick be in the range of 2 mm to 5 mm, and the amountof projection of the burning end portion of the wick from a support bein the range of 3.0 mm to 7.0 mm. With this arrangement, a burningportion of an ignitor which is suitable for practical use can beobtained.

In accordance with still another aspect of the present invention, thereis provided a structure of the burning portion of an alcohol-fueledignitor provided with a wick for drawing up fuel alcohol in a fuelreservoir by capillarity from one end portion thereof to the other endportion and burning the fuel alcohol at the other end portion whereinthe improvement comprises that said the other end portion of the wick atwhich the fuel alcohol is burnt is exposed in a surface area which isdetermined so that the flame length is not shorter than a predeterminedvalue just after ignition, is increased to a predetermined value in apredetermined time after ignition and is held at a saturated flamelength not larger than a predetermined flame length in an equilibratedstate. With this arrangement, an ignitor having excellent burningproperties can be easily obtained.

The wick employed in the present invention may be formed of a bundle ofglass fibers, a material obtained by forming a mixture of ceramic fibersand a small amount of binder into a plate about 3 mm to 5 mm thick anddrying it, or a material obtained by adding a small amount of binder andwater to ceramic fibers, extruding the resulting viscous fluid into around or rectangular bar by an extruder, and drying and solidifying thebar. Such a material is processed into a wick which can be used in anignitor to draw up fuel alcohol in a fuel reservoir by capillarity fromone end portion thereof to the other end portion and burning the fuelalcohol at the other end portion. The surface area of the exposedburning end portion of the wick is determined so that the flame lengthis not shorter than a predetermined value just after ignition, isincreased to a predetermined value in a predetermined time afterignition and is held at a saturated flame length not larger than apredetermined flame length in an equilibrated state.

Said one end portion (wicking end portion) and said the other endportion (burning end portion) of the wick may be either of the samematerial or of different materials.

As the fuel alcohol, for instance, a mixture of monovalent lower alcoholsuch as ethyl alcohol, methyl alcohol, propyl alcohol or the like with asaturated hydrocarbon such as hexane, heptane or the like for coloringthe flame may be employed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional view of a cigarette lighter inaccordance with a first embodiment of the present invention,

FIG. 2 is a schematic cross-sectional view of a cigarette lighter inaccordance with a second embodiment of the present invention,

FIG. 3 is a cross-sectional view of a basic sample of the ignitor usedin an experiment,

FIG. 4 is a graph showing the relation between the surface area of theexposed portion of the wick and the initial flame length for wicks ofglass fibers,

FIG. 5 is a graph showing the relation between the surface area of theexposed portion of the wick and the time required for the flame lengthto reach 25 mm for wicks of glass fibers,

FIG. 6 is a graph showing the relation between the surface area of theexposed portion of the wick and the saturated flame length for wicks ofglass fibers,

FIG. 7 is a graph showing the relation between the surface area of theexposed portion of the wick and the initial flame length for wicks ofceramic fibers,

FIG. 8 is a graph showing the relation between the surface area of theexposed portion of the wick and the time required for the flame lengthto reach 25 mm for wicks of ceramic fibers,

FIG. 9 is a graph showing the relation between the surface area of theexposed portion of the wick and the saturated flame length for wicks ofceramic fibers, and

FIGS. 10 to 19 are views showing an optimal range of the relationbetween the surface area of the exposed portion of the wick and variousdimensions of the wick in which a good burning state can be obtained forvarious materials of the wick and the cross-sectional shape of the samein the case where the wick is used in a cigarette lighter.

PREFERRED EMBODIMENT OF THE INVENTION

Embodiments of the present invention will be described with reference tothe drawings, hereinbelow.

First Embodiment

FIG. 1 shows in cross-section a disposable cigarette lighter inaccordance with a first embodiment of the present invention. The lighter1 comprises a fuel reservoir 2 in the form a tubular member closed atits one end. The inner space of the fuel reservoir 2 is filled withfibers (filler) 3 and an upper lid 4 is fixedly mounted on the upper endof the fuel reservoir 2. Thus a fuel storage portion 5 containingtherein fuel liquid is formed so that fuel liquid cannot be refilled.

For example, the fuel reservoir 2 is a molded product of polypropyleneand has an inner volume of 5 cm³. The fibers 3 are polypropylene fibers6 deniers in thickness and pressed into the fuel reservoir 2 in adensity of 0.1 g/cm³. The fibers 3 are impregnated with 4 g of fuelliquid which is a mixture of 95 wt % of ethyl alcohol and 5 wt % ofn-hexane.

A wick 6 is held by a wick holder 7 (support portion) to extendvertically into the fuel reservoir 2 through the upper lid 4. The wick 6comprising a burning portion 61 and a wicking portion 62 which areformed of different materials and are connected to each other by thewick holder 7 with the lower end portion of the burning portion 61 incontact with the upper end portion of the wicking portion 62. The wickholder 7 is in the form of a cylindrical member of metal.

The lower end portion of the wicking portion 62 of the wick 6 is incontact with the fibers 3 in the fuel reservoir 2 and draws up the fuelliquid impregnated in the fibers 3 by capillarity. When the portion ofthe burning portion 61 exposed above the wick holder 7 is ignited, thefuel liquid burns with flame.

The burning portion 61 of the wick 6 is formed by bundling glass fiberslike a rod. For example, each of the glass fibers is 6 μm in thickness,and the glass fibers are bundled into a rod which is 4 mmφ in thickness,10 mm in length and 150 mg/cm³ in fiber density. The burning portion 61projects upward by 5 mm from the upper end of the wick holder 7. Theexposed portion of the burning portion 61 of wick 6 projecting upwardfrom the holder 7 is 12.6 mm² in cross-sectional area and 75.4 mm² insurface area.

The wicking portion 62 of the wick 6 is formed by bundling and bondingacrylic fibers and is shaped like a rod having an enlarged head portion62 a. The wick 6 is formed by inserting the enlarged head portion 62 ainto the wick holder 7 into contact with the lower end portion of theburning portion 61, caulking the lower end portion of the holder 7 inthis state, and connecting the burning portion 61 and the wickingportion 62 into an integrated wick 6.

For example, the wicking portion 62 is 3.4 mm in the outer diameter ofthe enlarged head portion 62 a, 3 mm in length of the same, 3.0 mm inouter diameter of the leg portion and 37 mm in length of the same. Thethickness of the acrylic fibers forming the wicking portion are 3deniers, and the porosity of the wicking portion 62 is 60%.

A screw thread is formed on the outer peripheral surface of the wickholder 7, and the wick holder 7 is screwed into a threaded hole formedin the upper lid 4 with a seal ring 8 seated on the bottom of thethreaded hole.

An igniting mechanism 10 is mounted on the upper lid 4 to be opposed tothe upper end portion of the burning portion 61 of the wick 6. Theigniting mechanism 10 comprises a bracket 11 fixed to the upper lid 4, aflint 12 which is mounted in the bracket 11 to be movable up and down,and a wheel file 13 mounted on the top of the bracket 11. The flint 12is pressed against the surface of the wheel file 13 under the force of aspring 14 and when the wheel file 13 is rotated, spark is generatedtoward the wick 6.

A cap 16 for enclosing the burning portion 61 of the wick 6 and theexposed portion of the wick holder 7 is pivoted on an upper end of thefuel reservoir 2 above the upper lid 4 by a pin 17 to be rotatable aboutthe pin 17 between an opening position and a closing position where itencloses the burning portion 61 of the wick 6 and the exposed portion ofthe wick holder 7 to prevent volatilization of the fuel liquid. The cap16 is provided with an inner cap 16 a which is fitted on the wick holder7 and tightly encloses the wick 6. An O-ring 19 is fitted on the wickholder 7 and is engaged with the inner surface of the inner cap 16 a tomore tightly enclose the wick 6. A face plate 18 is positioned over theupper surface of the upper lid 4.

A vent hole 20 extends through the upper lid 4 along the inner surfaceof the wick holder 7 to communicate the inner space of the fuelreservoir 2 with the atmosphere. The vent hole 20 opens to theatmosphere in a position inside the space enclosed by the inner cap 16 aof the cap 16. The diameter of the vent hole 20 is substantially 1.0mmφ.

In the lighter 1 of this embodiment, the burning portion 61 of the wick6 was ignited and kept burning for 2 minutes. The flame length was 28 mmjust after ignition, was gradually increased to 45 mm about 30 secondsafter ignition, and was held at 45 mm thereafter. Thus, it was provedthat the lighter 1 of this embodiment could provide an optimal burningstate.

Second Embodiment

A cigarette lighter 1 in accordance a second embodiment of the presentinvention is shown in FIG. 2 and differs from that of the firstembodiment only in the structure of the wick 6 as can be seen from FIG.2. The wick 6 in the second embodiment is provided with a burningportion 63 formed of ceramic fibers in place of glass fibers.

The burning portion 63 is formed by adding a fine amount of organicbinder to ceramic fibers which are of ceramic materials containingtherein alumina and silica as major components and are 2.8 μmφ inthickness, forming the mixture of the ceramic fibers and the binder intoa plate about 3 mm thick, and cutting the plate into pieces which are 4mm in width and 10 mm in length. The packing density of the fibers ofthis burning portion 63 is 200 mg/cm³. The burning portion 63 projectsupward by 5 mm from the upper end of the wick holder 7. The exposedportion of the burning portion 63 of wick 6 projecting upward from theholder 7 is 12.6 mm² in cross-sectional area and 82 mm² in surface area.

The elements other than the burning portion of the wick 6 are same asthose in the first embodiment and the elements analogous to those shownin FIG. 1 are given the same reference numerals and will not bedescribed here.

In the lighter 1 of this embodiment, the burning portion 61 of the wick6 was ignited and kept burning for 2 minutes. The flame length was 30 mmjust after ignition, was gradually increased to 50 mm about 30 secondsafter ignition, and was held at 45 mm thereafter. Thus, it was provedthat also the lighter 1 of this embodiment could provide an optimalburning state.

The ignitor of the present invention, including those of the first andsecond embodiments, basically comprises a fuel reservoir for containingfuel alcohol the main component of which is alcohol, a wick for drawingup fuel alcohol in the fuel reservoir by capillarity from one endportion inserted into the reservoir to the other end portion and burningthe fuel alcohol at the other end portion and a support (wick holder)which holds the wick with said the other end portion projecting from thesupport, and is characterized in that the outer diameter of the burningend portion (said the other end portion) of the wick is in the range of2 mm to 5 mm, the length by which the burning end portion of the wickprojects from the support is in the range of 3.0 mm to 7.0 mm, and thesurface area of the burning end portion of the wick projecting from thesupport is in the range of 30 mm² to 170 mm² (30 mm² to 100 mm² in thecase of a cigarette lighter) when the wick is of glass fibers and is inthe range of 40 mm² to 170mm² (40 mm² to 100 mm² in the case of acigarette lighter) when the wick is of ceramic fibers.

These limits are for meeting the requirements that the flame length isat least about 20 mm just after ignition, is increased to about 25 mm in5 to 10 seconds after ignition and is held at a saturated flame lengthnot larger than 65 mm.

The values were determined through various experiments using a sampleshown in FIG. 3. In FIG. 3, a container 35 as a fuel reservoir is filledwith filler 34. The filler 34 is impregnated with fuel alcohol, and awicking portion 32 of a wick 30 is inserted into the container 35 incontact with the filler 34. An upper lid 36 is screwed on the open topof the container 35, and a jig holder 38 which holds the upper endportion of the wicking portion 32 is fixed to the upper lid 36 at thecenter thereof. A wick holding jig as a wick holder which holds aburning portion 31 of the wick 30 is mounted on the jig holder 38 sothat the lower end portion of the burning portion 31 is connected to theupper end portion of the wicking portion 32.

As the burning portion 31 of the wick 30, the glass fiber wick employedin the first embodiment or the ceramic fiber wick employed in the secondembodiment is used. The diameter of the fibers and the porosity of theburning portion 31 are suitably selected so that fuel liquid can bereplenished through the wicking portion 32 of acrylic fibers in anamount larger than that consumed by burning at the burning portion.

Though glass fiber wicks which were formed of glass fibers 6 μm thickand were 150 mg/cm³ in packing density were used, the glass fiber wicksmay be of somewhat different dimensions provided that fuel liquid can bereplenished to the surface of the wick in an amount larger than thatconsumed by burning at the burning portion. Similarly though ceramicfiber wicks which were formed of ceramic fibers 2.8 μm thick and were2000 mg/cm³ in packing density were used, the ceramic fiber wicks may beof somewhat different dimensions provided that fuel liquid can bereplenished to the surface of the wick in an amount larger than thatconsumed by burning at the burning portion. Further, though theexperiments were carried out by use of particular glass fibers andceramic fibers, results of the experiments may be applied to othermaterials provided that they are equivalent to the glass fibers andceramic fibers employed in heat-resistance and wicking and dispersingpower.

Glass fiber burning portions and ceramic fiber burning portions whichwere different in dimensions (the outer diameter and the length) wereprepared and wick holding jigs 37 which corresponded to the respectiveburning portions were prepared. Then burning test was effected whilechanging the length by which the burning portion projected from the jig37 and the surface area of the exposed portion. The results are shown inFIGS. 4 to 9. Fuel liquid employed in the first embodiment was employed.

FIGS. 4 to 6 show the relations between the initial flame length and thesurface area of the exposed portion of the burning portion, between thetime which the flame length took to increase to 25 mm and the surfacearea of the exposed portion of the burning portion, and between thesaturated flame length and the surface area of the exposed portion ofthe burning portion for outer diameters of glass fibers of 1 mmφ, 2 mmφ,3 mmφ, 4 mmφ and 5 mmφ and projecting lengths of 1 mm, 3 mm, 5 mm, 7 mmand 9 mm.

FIGS. 7 to 9 show the relations between the initial flame length and thesurface area of the exposed portion of the burning portion, between thetime which the flame length took to increase to 25 mm and the surfacearea of the exposed portion of the burning portion, and between thesaturated flame length and the surface area of the exposed portion ofthe burning portion for widths of 3 mm thick ceramic fiber wick of 1 mm,2 mm, 3 mm, 4 mm and 5 mm and projecting lengths of 1 mm, 3 mm, 5 mm, 7mm and 9 mm.

The surface area of the wicks are represented by values obtained bycalculating the areas of the side surfaces and the end surface on thebasis of the dimensions of the exposed portion of the wicks withmicroscopic unevenness on the surface of the wicks ignored.

As can be seen from FIG. 4, which shows the relation between the surfacearea of the wick and the initial flame length for the glass fiber wick,the surface area of the burning portion should be not smaller than 30mm² in order to obtain an initial flame length of not shorter than 20mm. When the surface area is 100 mm², the initial flame length is about35 mm and when the surface area is 170 mm², the initial flame length isabout 40 mm. These values of initial flame lengths are suitable for theignitor.

As can be seen from FIG. 5, which shows the relation between the timewhich the flame length took to increase to 25 mm and the surface area ofthe exposed portion of the burning portion in the case of glass fiberwicks, the surface area of the burning portion should be not smallerthan 30 mm² in order to keep the time which the flame length takes toincrease to 25 mm not longer than about 10 seconds.

As can be seen from FIG. 6, which shows the relation between thesaturated flame length and the surface area of the exposed portion ofthe burning portion in the case of glass fiber wicks, the saturatedflame length is 65 mm when the surface area is 170 mm² and the surfacearea may be not larger than 170 mm² in order to keep the saturated flamelength not longer than 60 mm to 70 mm. When the ignitor is a cigarettelighter, where the saturated flame length is to be not longer than 50 mmto 60 mm, the surface area should be not larger than 100 mm².

Further, as can be seen from FIG. 7, which shows the relation betweenthe surface area of the wick and the initial flame length for theceramic fiber wick, the surface area of the burning portion should benot smaller than 40 mm² in order to obtain an initial flame length ofnot shorter than 20 mm. When the surface area is 170 mm², the initialflame length is about 45 mm, which is considered to be an upperacceptable limit of the initial flame length for the ignitor. When thesurface area is 100 mm², the initial flame length is about 35 mm, whichis considered to be an upper acceptable limit of the initial flamelength for the cigarette lighter.

As can be seen from FIG. 8, which shows the relation between the timewhich the flame length took to increase to 25 mm and the surface area ofthe exposed portion of the burning portion in the case of ceramic fiberwicks, the surface area of the burning portion should be not smallerthan 40 mm² in order to keep the time which the flame length takes toincrease to 25 mm not longer than about 10 seconds.

As can be seen from FIG. 9, which shows the relation between thesaturated flame length and the surface area of the exposed portion ofthe burning portion in the case of glass fiber wicks, the saturatedflame length is 65 mm when the surface area is 170 mm² and the surfacearea may be not larger than 170 mm² in order to keep the saturated flamelength not longer than 60 mm to 70 mm. When the ignitor is a cigarettelighter, where the saturated flame length is to be not longer than 50 mmto 60 mm, the surface area should be not larger than 100 mm².

As can be understood from the aforesaid results of the experiments, thestructure of the burning portion of the alcohol-fueled ignitor can bemade optimal to obtain a good burning state by limiting the surface areaand the shape of the burning portion of the wick to the range describedabove, whereby design of the burning portion is facilitated.

FIGS. 10 to 19 show optimal ranges of the surface area of the wick forcigarette lighters in relation to the outer dimensions of the wick forthe cases where the wick is of a bundle of glass fibers which iscircular in cross-section, the wick is of ceramic fibers formed into abar which is circular in cross-section and the wick is of ceramic fibersformed into a bar which is rectangular in cross-section. The optimalranges are determined taking into account the size range, the mechanicalstrength and the mechanical applicability of the wick acceptable to acigarette lighter in addition to the range of the dimensions of the wickwhich governs the performance of the lighter on the basis of the resultof the aforesaid experiments. Practically, the space for mounting thewick and the amount of projection of the wick from the support must bedetermined taking into account the shape of the lighter and the like,and the overall shape of the wick can be determined according to thesurface area necessary to obtain desired burning properties. Thus theoverall shape and dimensions of the wick can be easily and efficientlydetermined.

What is claimed is:
 1. A structure of a burning portion of a wick for analcohol-fueled ignitor provided with a wick for drawing up fuel alcoholin a fuel reservoir by capillarity from a reservoir portion thereof tothe burning portion and burning the fuel alcohol at the burning portioncomprising: a wick burning portion to burn alcohol received bycapillarity from a reservoir portion disposed in an alcohol fuelreservoir formed of glass or ceramic fibers having a diameter in a ragefrom about 2.8 μm to about 6 μm bundled together in a rod shape at adensity in range from about 150 mg./cm³ to about 200 mg/cm³; and asupply of fuel alcohol in the burning portion of the wick; the burningportion of the wick being maintained in a rod shape and having anexposed surface area in a range from about 30 mm to about 170 mm² toprovide an initial flame length following ignition of at least about 20mm and a stabilized flame length in a range from about 45 mm to about 70mm.
 2. A structure of a burning portion as defined in claim 1 in whichthe ignitor is a cigarette lighter, and the burning portion of the wickhas an exposed surface area in a range from about 30 mm² to about 100mm².
 3. A structure of a burning portion as defined in claim 1 in whichthe ignitor is a cigarette lighter, and the burning portion of the wickhas an exposed surface area in a range from about 40 mm² to about 100mm².
 4. A structure of a burning portion as defined in claim 1 in whichthe circumference of the burning portion of the wick is in the rangefrom about 6 mm to about 20 mm.
 5. A structure of a burning portion asdefined in claim 1 in which the outer diameter of the burning portion ofthe wick is in the range from about 2 mm to about 5 mm.
 6. A structureof a burning portion as defined in claim 1 in which the length by whichthe burning portion of the wick projects from a support is in the rangefrom about 3.0 mm to about 7.0 mm.
 7. A structure of a burning portionof a wick for an alcohol-fueled ignitor provided with a wick for drawingup fuel alcohol in a fuel reservoir by capillarity from a reservoirportion thereof to the burning portion and burning the fuel alcohol atthe burning portion wherein the improvement comprises that comprising:said the other end portion of the a wick having a burning portioncomprising glass or ceramic fibers having a diameter in the range fromabout 2.8 μm to about 6 μm bundled together at a density in a range fromabout 150 mg/cm³ to about 200 mg/em³ in a rod shape at which the fuelalcohol is burnt; and a supply of fuel alcohol in the burning portion ofthe wick; the burning portion of the wick being maintained in a rodshape and having an exposed surface area which is selected so that theflame length is not shorter than about 20 mm just after ignitions isincreased to a length in a range from 45 mm to about 70 mm within abouttwo minutes after ignition and is held at a saturated flame length notlarger than about 70 mm.